Surgical robotic arm with wireless power supply interface

ABSTRACT

A proximal end portion of a robotic surgical arm is to be coupled to an adapter of a surgical robotic platform, for use during a surgical session at the platform, and then decoupled from the adapter for storage until being re-coupled for use during another surgical session at the platform. A resonant-mode transformer-coupled power converter is provided that has a secondary side and a primary side. The secondary side is in the arm and has a transformer secondary coil in the proximal end portion of the arm. The primary side has a transformer primary coil in the adapter. The primary and secondary coils are held at positions and orientations that enable mutual inductive coupling between them for operation of the power converter when the arm is coupled to the adapter. Other embodiments are also described and claimed.

FIELD

An embodiment of the invention relates to power supplies for surgicalrobotic arms. Other embodiments are also described.

BACKGROUND

In a surgical robotic system, a robotic arm that has a surgical toolattached to it its distal end is remotely operated by a surgeon.Applications include endoscopic surgery, which involves looking into apatient's body and performing surgery inside, for example the abdominalcavity, using endoscopes and other surgical tools that are attached tothe ends of several robotic arms. The system gives the surgeon aclose-up view of the surgery site, and also lets the surgeon operate thetool that is attached to the arm, all in real-time. The tool may be agripper with jaws, a cutter, a video camera, or an energy emitter suchas a laser used for coagulation. The tool is thus controlled in aprecise manner with high dexterity in accordance with the surgeonmanipulating a handheld controller.

In a typical surgical robotic session, there may be up to five arms thatneed to be ready for being deployed at a surgical robotic platform, suchas a table or bed on which the patient is resting. Installed within eacharm is a communications interface for receiving robotic commands from,and providing for example video data to, a computerized, surgicalconsole at which the surgeon sits while viewing a display screen thatshows the surgical site and while manipulating the hand controller. Alsoinstalled within each arm is arm joint driver and control circuitry, andtool driver and control circuitry; the arm joint driver and controlcircuitry can drive several motorized joints (actuators) to pivot ortranslate various links of the arm so that the distal end of the arm ismoved to a desired position as dictated by a user command; the tooldriver and control circuitry can drive for example a gripper or cutteractuator or an energy emitter in the surgical tool (as dictated by auser command.) Electrical power that supplies the communicationsinterface and the arm joint and tool driver and control circuitry may bedelivered to the arm, via a power cable that is separate from the armbut connected to the arm at one end and to the surgical robotic platformat another end (e.g., to a power supply at the surgical table.)Alternatively, power may delivered to the arm through the use of pogopins that come into electrical contact at a physical interface betweenthe arm and an arm adapter at the robotic platform, when the arm isattached to the arm adapter.

SUMMARY

An embodiment of the invention is a surgical robotic arm having awireless power supply interface to a surgical robotic platform. The armhas a proximal end portion and a distal end portion. The distal endportion is configured to receive a surgical tool. The proximal endportion is coupled to the surgical robotic platform, for example to anadapter of a surgical table on which a patient lies. The adapter adaptsthe surgical table to be coupled to the arm, so that the arm can be usedfor performing a surgery on the patient (while the patient is lying onthe surgical table.) In one embodiment, the functions of the adapter maybe viewed as being provided by the platform. The arm may have severallinkages and actuated (motorized) joints in between adjacent linkages.The linkages can thus be rotated about a pivot axis at each joint, orcan otherwise move, when power is supplied to arm joint driver circuitrythat drives the actuators. The proximal end portion of the arm is alsoconfigured for being decoupled from the adapter, for storage of the armuntil it is to be re-coupled for use during another surgical session atthe platform.

To achieve wireless or contactless electrical power transfer between thesurgical robotic platform and an electrical load in the arm, aresonant-mode transformer-coupled power converter is provided. The powerconverter has a primary side and a secondary side, where the primaryside has a transformer primary coil that is in the adapter (of theplatform), while the secondary side has a transformer secondary coilthat is in the proximal end portion of the arm. Once the arm is coupledto the adapter, the primary and secondary coils are held at relativepositions and orientations that enable mutual inductive coupling betweenthem, for proper operation of the power converter which delivers thefull power needed by the electrical load during the surgery. This avoidsthe need for pogo pins or separate power cables and power connectors, todeliver sufficient and reliable electrical power from the platform tothe electrical load that is in the arm. This solution is especiallydesirable since the arm has to not only be coupled to the adapter, butthen decoupled for storage once the surgery is over, and then recoupledto the adapter for another surgery, where this cycle repeats quite often(e.g., more than a handful of surgical sessions in a single day): thewireless power supply interface may be more reliable in the long termthan electrical contact-based connectors or pogo pins which can degradeover time particularly at high current levels and are difficult to keepclean. Also, the no-contact wireless power supply interface may bewashable in the operating room, another important convenience. Thesolution is also especially advantageous as there are several such armsthat are coupled to the robotic platform and are needed for simultaneousoperation during the surgery.

In one embodiment, the adapter at the robotic platform and the proximalend portion of the arm are configured so that the primary and secondarycoils are fixed in position relative to each other once the arm has beencoupled to the adapter, and remain in the same relative position whilethe arm is then used during a surgery.

In one embodiment, the adapter may have a pivot joint. A mechanicallatching mechanism is provided that latches the arm to the pivot jointin the adapter, in a detachable and re-attachable manner. The pivotjoint in the adapter enables the arm to rotate about a pivot axis of thejoint. In that case, the secondary coil and the primary coil remainfixed in position relative to each other but move as one with the arm asthe arm rotates around the pivot joint of the adapter.

As mentioned above, an electrical load in the arm is coupled to theoutput of the secondary side of the power converter. The load mayinclude a communications interface and motor and energy emitter drivercircuitry, where the latter drives several actuators (at multiple jointsincluding one or more at the surgical tool) and, if attached, an energyemitting surgical tool. The driving is in accordance with several armlinkage joint control signals and one or more tool control signals, thatare received by the communications interface, for example from a controltower. The control tower may have translated user commands received froma surgical console (signals that are sensing the orientation or positionof a handheld controller), and based on robotic feedback informationfrom the arm (e.g., accelerometer output data, thermal sensor outputdata, etc.) into robotic commands (arm linkage joint control signals inthe arm's joint space, and one or more tool control signals) for thearm.

In one embodiment, the actuator control signals as well as any othercontrol signals that are not part of the wireless electrical powerdelivery interface to the arm (which may be a resonant mode transformercoupled power converter as described above) are received and transmittedby the communications interface through a communications cable that mayrun from the arm to the control tower 3. Such a communications cable isthus in addition to the wireless power delivery interface, at each arm.The communications interface may also give robotic status feedback togenerate the next command, and other status such as power consumption,temperature from a sensor in the arm or in the tool, and position froman accelerometer in the arm or in the tool.

The above summary does not include an exhaustive list of all aspects ofthe present invention. It is contemplated that the invention includesall systems and methods that can be practiced from all suitablecombinations of the various aspects summarized above, as well as thosedisclosed in the Detailed Description below and particularly pointed outin the claims filed with the application. Such combinations haveparticular advantages not specifically recited in the above summary.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments of the invention are illustrated by way of example andnot by way of limitation in the figures of the accompanying drawings inwhich like references indicate similar elements. It should be noted thatreferences to “an” or “one” embodiment of the invention in thisdisclosure are not necessarily to the same embodiment, and they mean atleast one. Also, in the interest of conciseness and reducing the totalnumber of figures, a given figure may be used to illustrate the featuresof more than one embodiment of the invention, and not all elements inthe figure may be required for a given embodiment.

FIG. 1 is a pictorial view of an example surgical robotic system in anoperating arena.

FIG. 2A shows an embodiment of a robotic surgical arm that is uncoupledfrom an example surgical robotic platform.

FIG. 2B shows the arm in its coupled state.

FIG. 2C shows the arm in its coupled state and ready to be used in thesurgical operation.

FIG. 3 is a circuit schematic of an example resonant mode transformercoupled power converter that enables wireless power transfer to therobotic surgical arm.

FIG. 4A is a perspective view of two parts of a multi-part transformerthat may be used in the power converter.

FIG. 4B is a perspective view of the multi-part transformer in thecoupled state, where the constituent parts have been brought adjacent toeach other to enable mutual inductance coupling between the primary andsecondary coils.

DETAILED DESCRIPTION

Several embodiments of the invention with reference to the appendeddrawings are now explained. Whenever the shapes, relative positions andother aspects of the parts described in the embodiments are notexplicitly defined, the scope of the invention is not limited only tothe parts shown, which are meant merely for the purpose of illustration.Also, while numerous details are set forth, it is understood that someembodiments of the invention may be practiced without these details. Inother instances, well-known circuits, structures, and techniques havenot been shown in detail so as not to obscure the understanding of thisdescription.

Referring to FIG. 1, this is a pictorial view of an example surgicalrobotic system 1 in an operating arena. The robotic system 1 includes auser console 2, a control tower 3, and one or more surgical robotic arms4 at a surgical robotic platform 5, e.g., a table, a bed, etc. Thesystem 1 can incorporate any number of devices, tools, or accessoriesused to perform surgery on a patient 6. For example, the system 1 mayinclude one or more surgical tools 7 used to perform surgery. A surgicaltool 7 may be an end effector that is attached to a distal end of asurgical arm 4, for executing a surgical procedure.

Each surgical tool 7 may be manipulated manually, robotically, or both,during the surgery. For example, the surgical tool 7 may be a tool usedto enter, view, or manipulate an internal anatomy of the patient 6. Inan embodiment, the surgical tool 7 is a grasper that can grasp tissue ofthe patient. The surgical tool 7 may be controlled manually, by abedside operator 8; or it may be controlled robotically, via actuatedmovement of the surgical robotic arm 4 to which it is attached. Therobotic arms 4 are shown as a table-mounted system, but in otherconfigurations the arms 4 may be mounted in a cart, ceiling or sidewall,or in another suitable structural support.

Generally, a remote operator 9, such as a surgeon or other operator, mayuse the user console 2 to remotely manipulate the arms 4 and/or theattached surgical tools 7, e.g., teleoperation. The user console 2 maybe located in the same operating room as the rest of the system 1, asshown in FIG. 1. In other environments however, the user console 2 maybe located in an adjacent or nearby room, or it may be at a remotelocation, e.g., in a different building, city, or country. The userconsole 2 may comprise a seat 10, foot-operated controls 13, one or morehandheld user input devices, UID 14, and at least one user display 15that is configured to display, for example, a view of the surgical siteinside the patient 6. In the example user console 2, the remote operator9 is sitting in the seat 10 and viewing the user display 15 whilemanipulating a foot-operated control 13 and a handheld UID 14 in orderto remotely control the arms 4 and the surgical tools 7 (that aremounted on the distal ends of the arms 4.)

In some variations, the bedside operator 8 may also operate the system 1in an “over the bed” mode, in which the beside operator 8 (user) is nowat a side of the patient 6 and is simultaneously manipulating arobotically-driven tool (end effector as attached to the arm 4), e.g.,with a handheld UID 14 held in one hand, and a manual laparoscopic tool.For example, the bedside operator's left hand may be manipulating thehandheld UID to control a robotic component, while the bedsideoperator's right hand may be manipulating a manual laparoscopic tool.Thus, in these variations, the bedside operator 8 may perform bothrobotic-assisted minimally invasive surgery and manual laparoscopicsurgery on the patient 6.

During an example procedure (surgery), the patient 6 is prepped anddraped in a sterile fashion to achieve anesthesia. Initial access to thesurgical site may be performed manually while the arms of the roboticsystem 1 are in a stowed configuration or withdrawn configuration (tofacilitate access to the surgical site.) Once access is completed,initial positioning or preparation of the robotic system 1 including itsarms 4 may be performed. Next, the surgery proceeds with the remoteoperator 9 at the user console 2 utilizing the foot-operated controls 13and the UIDs 14 to manipulate the various end effectors and perhaps animaging system, to perform the surgery. Manual assistance may also beprovided at the procedure bed or table, by sterile-gowned bedsidepersonnel, e.g., the bedside operator 8 who may perform tasks such asretracting tissues, performing manual repositioning, and tool exchangeupon one or more of the robotic arms 4. Non-sterile personnel may alsobe present to assist the remote operator 9 at the user console 2. Whenthe procedure or surgery is completed, the system 1 and the user console2 may be configured or set in a state to facilitate post-operativeprocedures such as cleaning or sterilization and healthcare record entryor printout via the user console 2.

In one embodiment, the remote operator 9 holds and moves the UID 14 toprovide an input command to move a robot arm actuator 17 in the roboticsystem 1. The UID 14 may be communicatively coupled to the rest of therobotic system 1, e.g., via a console computer system 16. The UID 14 cangenerate spatial state signals corresponding to movement of the UID 14,e.g. position and orientation of the handheld housing of the UID, andthe spatial state signals may be input signals to control a motion ofthe robot arm actuator 17. The robotic system 1 may use control signalsderived from the spatial state signals, to control proportional motionof the actuator 17. In one embodiment, a console processor of theconsole computer system 16 receives the spatial state signals andgenerates the corresponding control signals. Based on these controlsignals, which control how the actuator 17 is energized to move asegment or link of the arm 4, the movement of a corresponding surgicaltool that is attached to the arm may mimic the movement of the UID 14.Similarly, interaction between the remote operator 9 and the UID 14 cangenerate for example a grip control signal that causes a jaw of agrasper of the surgical tool 7 to close and grip the tissue of patient6.

The surgical robotic system 1 may include several UIDs 14, whererespective control signals are generated for each UID that control theactuators and the surgical tool (end effector) of a respective arm 4.For example, the remote operator 9 may move a first UID 14 to controlthe motion of an actuator 17 that is in a left robotic arm, where theactuator responds by moving linkages, gears, etc., in that arm 4.Similarly, movement of a second UID 14 by the remote operator 9 controlsthe motion of another actuator 17, which in turn moves other linkages,gears, etc., of the robotic system 1. The robotic system 1 may include aright arm 4 that is secured to the bed or table to the right side of thepatient, and a left arm 4 that is at the left side of the patient. Anactuator 17 may include one or more motors that are controlled so thatthey drive the rotation of a joint of the arm 4, to for example change,relative to the patient, an orientation of an endoscope or a grasper ofthe surgical tool 7 that is attached to that arm. Motion of severalactuators 17 in the same arm 4 can be controlled by the spatial statesignals generated from a particular UID 14. The UIDs 14 can also controlmotion of respective surgical tool graspers. For example, each UID 14can generate a respective grip signal to control motion of an actuator,e.g., a linear actuator, that opens or closes jaws of the grasper at adistal end of surgical tool 7 to grip tissue within patient 6.

In some aspects, the communication between the platform 5 and the userconsole 2 may be through a control tower 3, which may translate usercommands that are received from the user console 2 (and moreparticularly from the console computer system 16) into robotic controlcommands that transmitted to the arms 4 on the robotic platform 5. Thecontrol tower 3 may also transmit status and feedback from the platform5 back to the user console 2. The communication connections between therobotic platform 5, the user console 2, and the control tower 3 may bevia wired and/or wireless links, using any suitable ones of a variety ofdata communication protocols. Any wired connections may be optionallybuilt into the floor and/or walls or ceiling of the operating room. Therobotic system 1 may provide video output to one or more displays,including displays within the operating room as well as remote displaysthat are accessible via the Internet or other networks. The video outputor feed may also be encrypted to ensure privacy and all or portions ofthe video output may be saved to a server or electronic healthcarerecord system.

A surgical robotic apparatus that has a wireless power supply interfaceis now described. Referring to FIG. 2A, an example of a robotic surgicalarm 4 is shown that is supported by a wheeled cart 43 and is ready to becoupled to the surgical robotic platform 5 for use during surgery uponthe patient 6. Here, a human patient is shown as an example, lying flaton the upper face of a surgical tabletop 34. In this example, thesurgical robotic platform 5 includes a surgical table 32 composed of thetabletop 34 on which the patient is lying on, and a table support 35such as a pedestal that has raised the tabletop 34 above a floor and isstabilized by a table base 36 that is on the floor. The table support 35may allow the tabletop 34 to have adjustable height, pitch, yaw or rollso as to enable a user such as a surgeon or assistant surgeon or nurseto perform a surgical procedure upon the patient 6 at a desiredorientation or position. The table support 35 may also enable thetabletop 34 to be adjustable horizontally, either in a length directionof the tabletop or in a width direction.

The robotic arm 4 has a proximal end portion 39 and a distal end portion38, between which are two or more (in the example shown here, three) armjoints 41. Each joint 41 is coupled to an adjacent pair of linkages. Inthe example shown, the arm 4 has three linkages but in general there maybe more. The joints are motorized to enable precise and dexterouspositioning of the distal end portion 38 to which a surgical tool 7 isattached, so that the distal end of the tool 7 can be preciselypositioned inside the patient 6 during surgery. The linkage at thedistal end portion 8 is configured to receive any one of several typesof surgical tools 7 (not shown) such as any one of those mentionedearlier in connection with FIG. 1.

The robotic surgical arm 4 also has its proximal end portion 39 that isconfigured, by virtue of its coupling member 40, to be coupled to anadapter 37 of the surgical robotic platform 5, for use during aparticular surgery session at the platform 5. In the example shown, theadapter 37 is secured to a surgical table 32. In other surgicalplatforms 5 however, the adapter 37 may be attached to for example acart, a ceiling, a sidewall, or even another suitable support structure.

There may be several adapters 37 coupled to (or part of) the surgicalrobotic platform 5, where each is to receive a respective arm 4, but inthe interest of conciseness FIG. 2A shows only one coupled to thesurgical table 32. Each adapter 37 has a mechanical latching mechanismthat latches the coupling member 40 of the arm 4 to the adapter 37, in asecure but detachable and re-attachable manner. The latching mechanismmay be manually (human user) actuated by a lever or other hand-operatedfeature, or it may be motorized and automatically controlled to latchitself once the coupling member 40 of the arm 4 has been placed intoposition in a complementary part of the latching mechanism, as seen inFIG. 2B for example. The adapter 37 may be a rigid structural supportmember that mechanically engages with the coupling member 40 at theproximal end portion 39 of the arm 4, so as to securely affix theproximal end portion of the arm 4 to the robotic platform 5 in what isreferred to here as its coupled state (during the surgical operation.)In the example shown, the adapter 37 is anchored to the tabletop support35, and extends laterally or horizontally outward from the tabletopsupport 35. The adapter 37 may be affixed to the tabletop support 35 soas to move as one with the former, as the position and orientation ofthe tabletop 34 is adjusted. Alternatively, the adapter 37 may beaffixed directly to the bottom or side of the tabletop 34, or directlyto the floor through a separate support member (that is separate fromthe tabletop support 35 and that may also be adjustable in position(height) or orientation.)

In the robotic surgery arm 4, the coupling member 40 is designed so thatit can be de-coupled from the adapter 37 once the surgery session hasended, so that the arm 4 can then be stored (e.g., on the cart 43),until the arm 4 is to be re-coupled to the adapter 37 for use duringanother surgical session at the platform. To illustrate this, FIG. 2Ashows how the height of a support member 42 of the cart 43 has beenadjusted so that a mouth of the coupling member 40 is brought to thesame height as the adapter 37. Next, the cart 43 is wheeled towards thesurgical table 32 until the mouth of the coupling member 40 engages theoutside end of the adapter 37, and is then locked into that coupledposition by the latching mechanism—see FIG. 2B. The cart 43 is thenwheeled away from the surgical table 32 thereby leaving behind thecoupled arm 4, as seen in FIG. 2C. The arm 4 is now ready for use in thesurgical operation. This procedure may be repeated to bring a total oftwo, three or more arms into their coupled states at the surgical table32, where each arm is locked into a fixed position at its respectiveadapter 37.

It should be noted that while the figures illustrate the example wherethe coupling member 40 of the arm 4 is a receptacle that receives andholds a “male” outside end of the adapter 37, an alternative is that theoutside end of the adapter 37 is configured as a receptacle thatreceives and holds a male coupling member 40.

In another embodiment of the invention, the adapter 37 can pivot arounda pivot joint (not shown), such that once the arm 4 is in its coupledstate, it too will pivot about the pivot joint. The mechanical latchingmechanism in that case may latch the coupling member 40 of the arm 4 toa complementary part of the adapter 37 that also pivots. The pivot axismay, for example, be a vertical axis. The mechanical latching mechanismfor this embodiment may also be configured to detach and re-attach thearm 4, by for example being manually (human user) actuated by a lever orother hand-operated feature, or it may be motorized and automaticallycontrolled to latch itself once the proximal end of the arm has beenplaced into position (at a complementary part of the latching mechanismthat is on the pivot joint.)

Still referring to FIGS. 2A-2C, these figures also illustrate howwireless power transfer can be achieved, from the surgical roboticplatform 5 to the electrical load in the arm 4, using a resonant modetransformer coupled power converter. The power converter may have aprimary side 47 at the surgical platform 5, e.g., attached to thesurgical table 32 as shown, that is coupled via mutual inductance to asecondary side 48 that is in the arm 4. The primary side 47 feeds powerto a transformer primary part 44 that is in the adapter 37, while atransformer secondary part 45 that is in the arm 4 receives that powerand feeds it to the secondary side 48. Examples of the transformerprimary and secondary parts are shown in FIG. 4A and in FIG. 4B to bediscussed below. More generally, the transformer primary part 44 has atransformer primary coil or multi-turn winding that may be housed in theadapter 37, and the transformer secondary part 45 has a transformersecondary coil or multi-turn winding that may be housed in the proximalend portion 39 of the arm, and more specifically in the coupling member40. The primary and secondary coils, or the primary part 44 and thesecondary part 45, may be rigidly held at fixed positions andorientations relative to each other (once the arm 4 is coupled to theadapter 37 as seen for example in FIG. 2B and in FIG. 2C) that enablemutual inductive coupling between them for operation of the powerconverter.

As mentioned above, the electrical load in the arm 4 is powered by theoutput of the secondary side 48 of the power converter. The load mayinclude a communications interface (communications circuitry), arm jointmotor driver and control circuitry including arm joint brake driver andcontrol circuitry (e.g., including brushless dc motor controllers),digital camera electronics, and energy emitter driver circuitry. Thecommunications interface may be, for example, a serial peripheralinterface bus, SPI, or other reliable digital communications interfacethat can deliver the arm linkage joint control and tool control signalsfrom a computer system at the surgical platform 5, e.g., the controltower 3. The control tower 3 may have translated user commands receivedfrom the surgical console 2 (signals that are sensing the orientation orposition of a handheld controller) and robotic feedback signals from thearm, into robotic commands, which may be the arm linkage joint controlsignals in the arm's joint space, and one or more tool control signalsfor the arm.

The arm joint motor driver and control circuitry drives or energizesseveral actuators (at multiple joints) in accordance with several armlinkage joint control signals that are received from the roboticsurgical platform 5 (e.g., from the control tower 3—see FIG. 1), by thecommunications interface. The digital camera electronics forms part of adigital camera in the surgical tool 7, e.g., an endoscopic camera. Theenergy emitter driver circuitry serves to energize one or more energyemitters that are in the surgical tool 7, such as a coagulation laser oran ultrasonic emitter. In one embodiment, the actuator control signalsas well as any other control signals that are not part of the wirelesselectrical power delivery interface to the arm 4 (which may include aresonant mode transformer coupled power converter as described above)are received and transmitted by the communications interface through acommunications cable that may run from the arm 4 to the robotic surgicalplatform 5, e.g., to the surgical table 32 and then to the control tower3.

FIG. 3 shows a circuit schematic of an example of the resonant modetransformer coupled power converter. The primary side 47 of the powerconverter has a group of solid state switches (depicted in the examplehere as metal oxide semiconductor field effect transistors) that routepower from a dc voltage rail at Vin(dc). The primary side 47 be housedin the adapter 37 as shown in FIG. 2A, but it could alternatively behoused in the tabletop support 35, in the base 36, or elsewhere on thesurgical table 32 or even in another element of the robotic surgicalplatform 5. The dc voltage rail at Vin(dc) may be produced by a platformpower supply (not shown), such as an ac-dc power converter that converts120 Vac/240 Vac “wall power” that may be available in the operatingroom, to a suitable dc voltage. The platform power supply supplies thepower that is drawn by the resonant mode power converter, which is inturn supplying the power that is drawn by the electrical load in thecoupled arm 4. In other words, the output Vout(dc) of the resonant modepower converter is a power supply to the communications interfacecircuitry and the arm joint and tool driver circuitry in the arm 4, asdescribed above. Just as an example, Vout(dc) may be 48 Vdc at 200Watts.

The switches in the primary side 47 route power from Vin(dc) to feed atransformer primary coil Lp. The latter is part of a primary sideresonant circuit, which is formed together with a capacitor Cp in theprimary side 47. The switches are turned on and turned off under controlof a switch mode power supply resonant controller also in the primaryside 47, e.g., a transformer driver that drives the primary sideresonant circuit with a 50% duty cycle square wave having a controlledworking (switching) frequency, in order to transfer power to thesecondary side 48 in a controlled, efficient manner, as needed by theelectrical load in the arm 4 that is coupled to the output of thesecondary side 48 at Vout(dc). The secondary side 48 has a transformersecondary coil Ls, which is part of a secondary side resonant circuitalong with capacitor Cs. There is mutual inductive coupling of magneticflux across a non-conductive (electrically insulating) gap 46 betweenthe coils, from the transformer primary part 44 to the transformersecondary part 45. This enables switch mode power transfer from theprimary side 47 to the secondary side 48. The power required by the loadmay be met by changing the switching frequency of the control signal ofthe resonant controller in the primary side 47, e.g., by matching theswitching frequency with the resonance frequency of the L-C basedresonant circuit in the primary side in order to increase powertransfer. The closer the switching frequency to the resonant frequency(fr) of Lp and Cp, the higher the voltage at the secondary side 48. WhenVout is lower than the setting voltage, which may be for example 48V,the feedback signals make the controller switching frequency closer tothe resonant frequency (fr) to make Vout higher. When Vout great thanthe setting voltage, the feedback signal can force the switchingfrequency away from fr to make Vout lower. The feedback signal is ananalog signal, e.g., Vfb, and as explained below may be converted into aPWM waveform before being passed over an optical interface over the gap,or alternatively by the communication interface circuitry mentionedabove. Note that the turns ratio of the primary coil to the secondarycoil need not be 1:1.

The ac (switched) voltage at the output of the resonant circuit Ls-Cs isconverted into dc by a rectifier (in this example, a full wave rectifiercomposed of the four diodes as shown) and then filtered by a filtercapacitor Cf, resulting in the output voltage Vout(dc). If regulation ofVout(dc) is desired, then this may be achieved by configuring theresonant controller to vary the switching frequency of its control ofthe switches, in a feedback controlled manner. This would be in responseto a feedback voltage Vfb that represents an error or difference betweena reference voltage Vref and the power converter output voltageVout(dc). The feedback voltage Vfb may be provided to the resonantcontroller, not in its original form but rather in the form of Vfb′,where Vfb is converted in the secondary side 48 into a PWM signal,before it is then transmitted by an optical transmitter 54 of an opticalcoupler to an optical receiver 55 in the primary side 47, where it isthen converted back into analog form as Vfb′ before being used by theresonant controller. The technique of converting the feedback signalinto digital form (e.g., as a PWM signal) for its transfer from the arm4 to the robotic surgical platform 5 increases immunity to noise duringthe transfer. Other techniques for delivering the feedback voltage Vfbfrom the secondary side 48 to the primary side 47 in a wireless orcontact-less manner across the electrically insulating gap 46 includethe use of an auxiliary transformer. In yet another embodiment, thefeedback voltage Vfb′ is received in the primary side 47 via a cabledcommunications interface with the secondary side 48 in the arm 4, e.g.,the same SPI that is used by the communications interface in the arm 4for receiving the robotic commands from the control tower 3.

FIG. 4A and FIG. 4B are perspective views of the two parts of an examplemulti-part transformer, that may be used in the resonant modetransformer coupled power converter of FIG. 3. The transformer primarypart 44, which is in the proximal coupling member 40 of the arm 4 (seeFIGS. 2A-2C), and has a primary coil that terminates in a pair ofprimary terminals 51. There is also the transformer secondary part 45,which is in the adapter 37 and has a secondary coil that terminates in apair of secondary terminals 52. FIG. 4A shows the transformer in itsun-coupled state, when the arm 4 has been de-coupled from the adapter 37for purposes of storage—see FIG. 2A: the primary part 44 is spaced sofar apart from the secondary part 45 that there is insufficient mutualinductive coupling between them (to transfer enough power to supply theelectrical load in the arm 4.) In contrast, FIG. 4B shows thetransformer in its coupled state, when the arm 4 is coupled to theadapter 37—see FIG. 2C. There, the primary part 44 has been broughtclose enough to the secondary part 45 such that the two are separatedonly by the gap 46—see FIG. 3. This state allows sufficient power to betransferred from the primary to the secondary (so as to supply theelectrical load in the arm 4.)

In the particular example of FIG. 4A and FIG. 4B, the multi-parttransformer may have a core form or a shell form in which each of theprimary coil and the secondary coil is wound around a respective,magnetic or ferromagnetic core or shell portion that may be composed oflaminated steel (steel sheets lying in the x-y plane and stacked in thez-direction.) As seen in the figures, in each of the primary part 44 andthe secondary part 45 of the transformer, there is a pair of supportplates that support the coil of that part, one on the left side andanother on the right side of the coil. The four support plates are allparallel to each other, and the two inner ones may be separated by lessthan 5 mm once the arm 4 has been coupled to the adapter 37 (resultingin the coupled state shown in FIG. 4B.) For each of the primary part 44and the secondary part 45 of the transformer, the core form or shellform part may be composed of magnetic or ferromagnetic material such aslaminated steel.

The transformer primary part 44, including the primary coil, may beentirely encapsulated by insulating material, as is the secondary part45. This may ensure that the coils are not exposed to touch, which isparticularly desired when the coils support peak to peak voltages thatare greater than 60 Vac. The encapsulation material may be selected tohave sufficient magnetic permeability, e.g., containing ferriteparticles, and it may fill the entire gap 46 as seen in FIG. 4B, wherethe flat outside face of the encapsulated primary part 44 will abut theflat outside face of the encapsulated secondary part 45 (so as to enableefficient mutual inductive coupling between the primary coil and thesecondary coil at the switching frequency of the power converter.)

As seen in the figures, each part of the multi-part transformer may havea flat face that becomes aligned with, and is held at a fixed distancefrom, the other part of the multi-part transformer, when the arm 4 hasbeen coupled to the adapter 37. Note that perfect alignment in the x, yand z-axes that are shown is not necessary during working or operationof the arm 4. However, misalignment in any of the axes may result in areduction in efficiency of the power transfer. In one embodiment, oncethe arm 4 is coupled to the adapter 37, there may be an electricallyinsulating gap 46 of no more than 5 mm between the primary coil and thesecondary coil, which may ensure sufficient mutual inductive coupling todeliver at Vout(dc), 200 W at 48V. In one embodiment, the flat outsidefaces of the encapsulated primary and second parts abut each other,while maintaining the gap 46 between the primary and secondary coils.

In the example of FIGS. 2A-2B, the primary and secondary coils arepositioned such that the mutual inductive coupling (magnetic flux)between them is through the lateral or side faces of their respective“housings”, which are the adapter 37 and the coupling member 40,respectively. They could however be positioned differently. For example,the primary and secondary coils could be positioned such that the mutualinductive coupling is through the top face of the adapter 37 and theinner top face of the coupling member 40, at the interface or boundarybetween the two housings. In another example, the primary and secondarycoils could be positioned so that the mutual inductive coupling isthrough the bottom face of the adapter 37 and the inner bottom face ofthe coupling member 40.

In the example of FIGS. 2A-2B, the lateral or side faces of the twohousings of the adapter 37 and the coupling member 40 define a verticalinterface or boundary, through which the magnetic flux lines of themutual inductive coupling pass from one housing to the other. Thissuggests that the primary and secondary coils could have the sameorientation, e.g., the length axes of both may be vertical, as seen inFIG. 4B. But their orientation may be different such that the interfaceor boundary between them need not be vertical. For example, the twocoils could be tilted in the same direction, such that the magnetic fluxlines of their mutual inductive coupling cuts through a diagonalboundary line (rather than a vertical boundary as seen in FIG. 4B.) Inother words, the primary and secondary coils may be oriented differentlythan shown in FIGS. 2A-2C and in FIG. 4B, so that the magnetic fluxlines of their mutual inductive coupling cross an interface boundarythat is not vertical.

While certain embodiments have been described and shown in theaccompanying drawings, it is to be understood that such embodiments aremerely illustrative of and not restrictive on the broad invention, andthat the invention is not limited to the specific constructions andarrangements shown and described, since various other modifications mayoccur to those of ordinary skill in the art. For example, while FIG. 3depicts a resonant mode transformer coupled power converter having aparticular arrangement of a full bridge switch circuit and a seriesresonant circuit in the primary side 47, and a series resonant circuitand a full wave diode-based rectifier in the secondary side 48, otherarrangements for the switches and resonant circuits of the powerconverter are possible (e.g., a half bridge switch circuit, a parallelresonant circuit, a series-parallel resonant circuit, and an activerectifier.) The description is thus to be regarded as illustrativeinstead of limiting.

What is claimed is:
 1. A surgical robotic apparatus comprising: asurgical robotic arm configured to be removably coupled to a surgicalrobotic platform for surgery and decoupled from the platform forstorage; and a transformer secondary coil of a transformer-coupled powerconverter that also has a transformer primary coil, wherein thesecondary coil is in the arm and the primary coil is in the platform andthere is inductive coupling between the primary and secondary coils foroperation of the power converter when the arm is coupled to theplatform.
 2. The apparatus of claim 1 wherein the arm comprises acoupling member formed as a receptacle to receive an adapter of theplatform, wherein the coupling member has a mechanical latchingmechanism that latches the coupling member to the adapter, in adetachable and re-attachable manner.
 3. The apparatus of claim 1 whereinthe arm comprises: a male coupling member that is to be received by anadapter of the platform, wherein the male coupling member has amechanical latching mechanism that latches the male coupling member tothe adapter, in a detachable and re-attachable manner.
 4. The apparatusof claim 1 wherein the secondary coil and the primary coil are fixed inposition relative to each other once the arm has been coupled to theadapter.
 5. The apparatus of claim 4 wherein the secondary coil is partof a second part of a multi-part transformer that also has a first part,wherein the multi-part transformer is of a core form or a shell form inwhich each of the primary coil and the secondary coil is wound around arespective, magnetic or ferromagnetic core or shell portion, and whereinthe second part of the multi-part transformer is in the arm while thefirst part is in the platform.
 6. The apparatus of claim 5 wherein thefirst part of the multi-part transformer has a flat face that becomesaligned with, and is held at a fixed distance from the second part ofthe multi-part transformer when the arm has been coupled to theplatform, and wherein in that position there is an electricallyinsulating gap between the primary coil and the secondary coil.
 7. Theapparatus of claim 1 wherein the primary and secondary coils are partsof a multi-part transformer, wherein the multi-part transformer is of acore form or a shell form in which each of the primary coil and thesecondary coil is wound around a respective, magnetic or ferromagneticcore or shell portion, and wherein the part of the multi-parttransformer that has the secondary coil is in the arm while the partthat has the primary coil is in the platform.
 8. The apparatus of claim7 wherein the multi-part transformer comprises a first support platethat supports the primary coil, and a second support plate that supportsthe secondary coil, and wherein the first and second supports areparallel to each other and separated when the arm has been coupled tothe platform.
 9. The apparatus of claim 1 wherein the secondary coil ispart of a second part of a multi-part magnetic transformer that also hasa first part, wherein the multi-part magnetic transformer is of acoreless form, and wherein the second part of the multi-part transformeris in the arm while the first part is in the platform.
 10. The apparatusof claim 1 further comprising an electrical load coupled to an output ofthe power converter, wherein the electrical load comprises: acommunications interface in the arm, configured to receive an armactuator control signal; and motor driver circuitry in the arm that iscoupled to the communications interface and configured to be controlledby the arm actuator control signal.
 11. The apparatus of claim 10wherein the power converter comprises an optical coupler having atransmitter that is affixed to the arm and transmits a feedback signalderived from the output of the power converter, and wherein the opticalcoupler has a receiver that is affixed to the platform and receives thefeedback signal when the arm is coupled to the platform.
 12. Theapparatus of claim 2 wherein the adapter comprises a pivot joint thatenables the coupling member to rotate about a pivot axis of the joint.13. The apparatus of claim 1 wherein the power converter comprises anoptical coupler having a transmitter that is affixed to the arm andtransmits a feedback signal derived from the output of the powerconverter, and wherein the optical coupler has a receiver that isaffixed to the platform and receives the feedback signal when the arm iscoupled to the platform.
 14. The apparatus of claim 3 wherein theadapter comprises a pivot joint that enables the coupling member torotate about a pivot axis of the joint.
 15. A method for operating asurgical robotic apparatus, the method comprising: coupling a surgicalrobotic arm to a surgical robotic platform for surgery; and initiatingwireless power delivery to the arm through a transformer secondary coilof a transformer-coupled power converter that also has a transformerprimary coil, wherein the secondary coil is in the arm and the primarycoil is in the platform and there is inductive coupling between theprimary coil and the secondary coil for operation of the power converterwhen the arm is coupled to the platform.
 16. The method of claim 15further comprising decoupling the arm from the platform for storage ofthe arm.